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When driving low speed and A/C on car gets hot.

ripple1973

ripple1973

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When i have the A/C on and driving down the highway car dosent get hot. but if i am driving low speeds or at the light the car will heat up. I have replaced in the last year Compressor, all the lines, accumulator, orifice tube 4 Core aluminium radiator, Severe Duty fan, and external transmission cooler. Also replaced condenser 3 years ago with a parallel flow condenser. There is no trash in the condenser

overheat.jpg
 
You probably aren't getting enough air flow.
The condenser job is to give up heat, that heat goes into radiator.
Do you have a good fitting shroud?
How many blades on fan, fan clutch?
 
I will look tomorrow about how many fan blades. I have been told to get a electric fan on the condenser and have it come on when turning on A/C
 
Have you checked the actual Temps at the thermostat neck or at the hoses? Sometimes my gauge will go up like yours but infrared gun shows me 190 at thermostat and I can hold my hand on the radiator cap.... definitely not overheating. I've replaced the gauge, the sender, radiator, etc
 
Wes Harden said:
You probably aren't getting enough air flow.
The condenser job is to give up heat, that heat goes into radiator.
Do you have a good fitting shroud?
How many blades on fan, fan clutch?
Click to expand...

Have Stock Fan shroud with a 5 blade fan and fan clutch has been replace with a heavy duty Fan clutch.
 
Can you hear the fan clutch lock up? also the middle of fan blade should be at edge of shroud.

and check between the condenser and rad for debris grass animal fur what not.
 
fordsucks! said:
Have you checked the actual Temps at the thermostat neck or at the hoses? Sometimes my gauge will go up like yours but infrared gun shows me 190 at thermostat and I can hold my hand on the radiator cap.... definitely not overheating. I've replaced the gauge, the sender, radiator, etc
Click to expand...

I have thought of this one other thing i have done was replaced coolant temperature sensor that is in between 1 & 3 cylinder. I thought for the longest time it was located on the thermostat housing. I need to buy a infrared thermometer
 
Wes Harden said:
Can you hear the fan clutch lock up? also the middle of fan blade should be at edge of shroud.

and check between the condenser and rad for debris grass animal fur what not.
Click to expand...

Also how can you hear it lock up? Ok i will check for debris
 
If I understand this, your engine is over heating, or not heating up ? you might also want to check if the fan clutch is Ok, they wear out after 25 years. You should have a 16 PSI cap on the radiator. And as said, you need to make sure the radiator is getting all the cool air as possible, IE: the fan shroud. needs to be in good shape and If my 88 is any example, you have a six bladed fan on your truck. Now this is just me, but when I restored my 1988 K5, I put a extra heavy duty transmission cooler in place of the smaller old unit, and I placed 1" sections of radiator hose inbetween the new cooling unit and the radiator, and the plastic ties go through the center of the hose pieces. This gives the radiator and the cooler some cool fresh air to be drawn in from the sides, See, you have the Radiator, the A/C Condenser and the Transmission cooler all stacked on top, or in front of each other. By the time any air gets back to the radiator it's pretty warm by then. So this gives the radiator some fresh air from the sides of the front. I'd pressure test the whole system. I hope I have helped.
 
Killain said:
If I understand this, your engine is over heating, or not heating up ? you might also want to check if the fan clutch is Ok, they wear out after 25 years. You should have a 16 PSI cap on the radiator. And as said, you need to make sure the radiator is getting all the cool air as possible, IE: the fan shroud. needs to be in good shape and If my 88 is any example, you have a six bladed fan on your truck. Now this is just me, but when I restored my 1988 K5, I put a extra heavy duty transmission cooler in place of the smaller old unit, and I placed 1" sections of radiator hose inbetween the new cooling unit and the radiator, and the plastic ties go through the center of the hose pieces. This gives the radiator and the cooler some cool fresh air to be drawn in from the sides, See, you have the Radiator, the A/C Condenser and the Transmission cooler all stacked on top, or in front of each other. By the time any air gets back to the radiator it's pretty warm by then. So this gives the radiator some fresh air from the sides of the front. I'd pressure test the whole system. I hope I have helped.
Click to expand...

My engine is over heating. There is 2" between my transmission cooler and my condenser. The fan Shroud is in good shape 5 bladed fan, New Severe Duty Fan Clutch. Yes i do need to pressure test. Also i thought these vehicles Self bleed air from the cooling system am i correct?
 
Yes ! Once the engine heats up to operating temperature, and shut off, any excess coolant is pushed out the overflow, and then when cooled down, it causes a vacuum in the cooling system and any coolant is drawn back into the radiator from the overflow tank. but you want to make sure the hose from the radiator to the reservoir or overflow tank is in good shape and not allowing any of the vacuum to lose suction though a poor clamp or fitting. This is the tank or overflow reservoir and the connecting hose needs to be tight. I just finished the rebuilding of my overflow reservoir and the hose if you need that info, it is a special hose that replaces the original.

s-l500.jpg
 
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when a fan clutch locks up the fan will get louder, and if you have the hood up more air will move through engine compartment.

Pretty hot in San Antonio atm? how does the ac cool after being parked in hot sun ?

I your truck a 73 ? with an A6 compressor ? should get nice and cold inside. I added a 10" condenser fan for when we are in AZ not really necessary in So cal.

IMG_20190611_160823.jpg
 
Killain said:
Yes ! Once the engine heats up to operating temperature, and shut off, any excess coolant is pushed out the overflow, and then when cooled down, it causes a vacuum in the cooling system and any coolant is drawn back into the radiator from the overflow tank. but you want to make sure the hose from the radiator to the reservoir or overflow tank is in good shape and not allowing any of the vacuum to lose suction though a poor clamp or fitting. This is the tank or overflow reservoir and the connecting hose needs to be tight. I just finished the rebuilding of my overflow reservoir and the hose if you need that info, it is a special hose that replaces the original.

View attachment 344609
Click to expand...
I never thought of that thank you for explaining that. So it is a special hose did you get it from LMC?
 
Wes Harden said:
when a fan clutch locks up the fan will get louder, and if you have the hood up more air will move through engine compartment.

Pretty hot in San Antonio atm? how does the ac cool after being parked in hot sun ?

I your truck a 73 ? with an A6 compressor ? should get nice and cold inside. I added a 10" condenser fan for when we are in AZ not really necessary in So cal.

View attachment 344610
Click to expand...
I have a 85 K5 Blazer. WIth a R4 Compressor. It is hot and humid here in SA. if the car is in the sun it takes 2 mins to star cooling the air. If i have to put a condenser fan i will have to move my trans cooler
 
Yeah I wouldn't remove my trans cooler esp if you have 700r4. As long as the ac works satisfactory, in 88 GM started putting an 8" condenser fan on the Suburban's and K5's to help get the cab cooler.
We had a customer in AZ the 87 Suburban would sit all day in the sun, would be 140* inside. A/c took forever to get the temp down to 80*. In a small town, you'd be where you were going be fore it would be "cool". Added the condenser fan, under warranty. Fan helped out the customer was happier, but he sill bitched to GM area rep, we got a visit, Showed the Rep the problem with a new Suburban on the lot. Next model year had a fan.
 
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ripple1973 said:
When i have the A/C on and driving down the highway car dosent get hot. but if i am driving low speeds or at the light the car will heat up. I have replaced in the last year Compressor, all the lines, accumulator, orifice tube 4 Core aluminium radiator, Severe Duty fan, and external transmission cooler. Also replaced condenser 3 years ago with a parallel flow condenser. There is no trash in the condenser

View attachment 344566
Click to expand...
What kind of water pump do you have and when was the last time it was replaced? I put a HD water pump on the Jimmy which has a 400, and also added an external oil cooler with a remote filter mount. Almost all vehicles these days have an oil cooler of some sort so figured the Jimmy needed one. My temps run just over thermostat rating, transmission seems to run cooler too. I also have an additional temp sensor that is right at the radiator hose so that is temp that the engine actually sees. I kept the original sensor and gauge as a backup. I need to do a test next time it gets above 110 here and see what the temps are in a drive thru. I may add a small electric fan.
 
Overheating eh? Sounds like everybody has covered all the bases...except...Which way does your water pump pulley spin? Clockwise (CW) or counterclockwise (CCW)? I've seen where the fan clutch was spinning the wrong way! Look at the back of the fan clutch for an arrow indicating which way the fan clutch should spin. Same for the coolant pump. CW or CCW? oh, and make sure the fan blades correlate to the system, CW or CCW. Simple error to make (ask me how I know) the part was packaged wrong . Same goes for the coolant pump, CW or CCW? I always replace with a HD pump if available, just because!

If all is correct install an auxilary electric fan to come on with the A/C like I did. Install the largest fan that will fit, pusher or puller. Problem solved (hopefully). Oh...one other thing..are you using coolant and have to top off frequently and cannot find a leak? You may want to have a block leak check done to see if you have a head gasket leak. Small item that is a possibility too. As far as the fan clutch, OEM or aftermarket? I used the OEM HD big block fan clutch. $$$ but well worth it. Cool air has a price, especially in hot/humid climates.
 
ripple1973 said:
I never thought of that thank you for explaining that. So it is a special hose did you get it from LMC?
Click to expand...

Ah, No. I'm a little crazy about finding the "Exact GM Stock Item" when doing this kind of a restoration, no matter what area. The correct hose is a Gatts #27556. It is a non reinforced thin walled hose clamped by a semi special one-time clamping tool, and a spring clamp at the radiator. Here are the two different clamps, and the tool to connect the hose to the reservoir, and the one to make the connection at the radiator. I had to buy a whole collection to get my 1 clamp. So If you give me your address or a address, I will send you two brand new clamps !

SANY0193.JPG
 
Killain said:
Ah, No. I'm a little crazy about finding the "Exact GM Stock Item" when doing this kind of a restoration, no matter what area. The correct hose is a Gatts #27556. It is a non reinforced thin walled hose clamped by a semi special one-time clamping tool, and a spring clamp at the radiator. Here are the two different clamps, and the tool to connect the hose to the reservoir, and the one to make the connection at the radiator. I had to buy a whole collection to get my 1 clamp. So If you give me your address or a address, I will send you two brand new clamps !
Click to expand...

Thank you I like to do things right
Douglas Krasiewski
5415 Vista Creek
San Antonio Tx 78247
 
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